• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.41-47
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• 2024

Recently, as the practical application and commercialization of unmanned aerial vehicles (UAVs) is pursued, interest in ensuring the safety of the UAV is increasing. Because UAV accidents can result in property damage and loss of life, it is important to develop technology to prevent accidents. For this reason, a technique to detect the abnormal flight state of UAVs has been developed based on the AutoEncoder model. However, the existing detection technique is limited in terms of performance and real-time processing. In this paper, we propose a U-Net based abnormal flight detection technique. In the proposed technique, abnormal flight is detected based on the increasing rate of Mahalanobis distance for the reconstruction error obtained from the U-Net model. Through simulation experiments, it can be shown that the proposed detection technique has superior detection performance compared to the existing detection technique, and can operate in real-time in an on-board environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.871-876
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• 2016

Abnormal odor similar with burning smell often appears at the cockpit in the beginning of ultra-sonic aircraft without air filter due to the heating of production materials remained at the bleed air duct. Sources of the odor should be removed by burn-in test before test flight in order to prevent pilot confuses order with emergency such as fire of engine. However, the present method cannot prevent abnormal odor completely at the high altitude flight because maximum temperature of flight is higher than it of burn-in-test. This paper suggests burn-in test improved based on the analysis of thermal conditions of high altitude flight. It is verified that the existing burn-in test cannot cover thermal conditions of high altitude flight due to the discontinuous flow control, high change rate of temperature per unit time and difference between limit temperature of condenser and turbine. In order to overcome the limitations of current methods, the new burn-in test with continuous flow control are suggested. The continuous flow control are achieved by ram air inlet control. The effect of suggested method are verified by ground tests and flight tests. The results show the bleed air temperature can cover the temperature of high altitude flight and prevent abnormal odor at the flight test.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.10 no.1
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• pp.57-68
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• 2002

The economical aspects should be evaluated to decide the LCC(Life Cycle Cost) of the long life facilities or equipments. Airplane operators evaluate the economical aspects to decide whether they maintain the existing airplane or substitute the new one. This paper presents economic life cycle and economic life cost for both Cessna 172R and Mooney 20J that are operated for flight training in 'H' University. The residual value that is used to calculate the capital recovery rate of the airplane is calculated based on the data from Blue Book published in USA. The annual equivalent on operation cost is calculated based on the 500 flight hours per year which is the annual flight hour for the airplane in 'H' university. This paper showed that economic life cycle of Cessna 172R is nine years since it was introduced in 2001, and Mooney 20J which was introduced in 1991 exceeds the economic life cycle in 2002.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.21-29
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• 2004

Numerical analysis of aerodynamic heating for KPSAM is performed using aerodynamic heating model suitable to KPSAM, which has complex flow field resulting from the spike attached to the dome, such as large separation area and the strong shock/boundary layer interaction region around reattachment point on the dome. The aerodynamic heating model is validated and modified through the comparison between the flight test measurement and the thermal analysis results. TFD temperature sensors are installed on the dome to measure surface temperature during the flight. Computation results, obtained from the heat transfer analysis on the sensors, agree well with flight test data. The aerodynamic heating model provides heat transfer rate into surface as a boundary condition of unsteady 1D/axisymmetric thermal analysis on the missile structure. The axisymmetric thermal analysis using FLUENT is more versatile than the 1D analysis and can be applied to the heating problem related with complex structures and multi-dimensional heat transfer problems such as prediction of temperature rise at contact surface of different materials.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.69-82
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• 2011

This paper tried to find out what the main factors are to impact on satisfaction level of transit passengers at Incheon airport. Incheon airport has made lots of transit facilities and services to attract transit passengers from neighboring airports to increase transit rate as high as advanced foreign airports such as Heathrow, Schiphol and Hong Kong. A survey was performed on 450 transit passengers resting at airport transit lounge in airside area. According to the result, it was found out to be significant factors affecting satisfaction of transit that convenience of security screening, price of duty-free product, a direction board & signage and terminal orientation among Chinese transit passengers. On the other hands, it seemed that Japanese transit passengers thought diversity of airline routes, convenient transfer flight schedule, total transit time and terminal orientation are major variables affecting their satisfaction. Considering the effect of demographic factors, Chinese passenger's satisfaction was more affected by age, travel purpose, the number of travel per year and flight destinations. However, Japanese transit passenger's satisfaction was only affected by the flight destinations, especially willing to travel to North America and Europe.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.209-216
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• 2015

It is difficult to detect, track and intercept ballistic missile because of its high speed and short flight time from launching to target area. In order to increase the success rate of a ballistic missile interceptor, it is important to track the flight trajectory for a long time after the detection in the early launch. Radar Cross Section(RCS) of the target is important when the target to be detected by the radar, and the difference between the RCS value greatly changes depending on the viewing direction during the flight missile trajectory. In this paper, it is assumed that a ballistic missile is launched at east coast of North Korea, observe that missile by a land based radar and sea deployed radar. And it is analyzed and compared that RCS difference of ballistic missile.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.992-997
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• 2009

This paper focuses on the calculation of the missile angular velocity under the reduced sensor condition and its verification using the Flight Motion Simulator(FMS). The missile angular velocity is usually measured by the body gyroscopes, but we assume that the inertial sensors on the missile body are in the absence of pitch and yaw gyroscopes. Under this reduced sensor condition, this paper shows the missile angular velocity can be calculated by using the gimbal seeker gyroscope, the roll body gyroscope, the gimbal angle and its rate. The FMS experiment was carried out to verify the proposed algorithm.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.2
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• pp.62-67
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• 2009

LOSA is a flight safety program that analyses human errors in normal operations. Trained pilot observers monitor the normal flights at the observer seat. LOSA is a proactive non jeopardy data collection tool using threat and error management(TEM) as a framework. With the analysis of crew behaviors through LOSA with The LOSA collaborative(TLC), the airlines can identify the behaviors of the crew during normal operations. The major objective of LOSA is to measure how the crew manage threats, errors and undesired aircraft deviations in the cockpit on day to day operations. The airlines are able to set up effective TEM training with practical six generation Crew recourse management(CRM) with data of error from LOSA instead of theoretical CRM courses. The Airlines can use TEM as an integral part of a Safety Management System(SMS) and uses monitoring and cross-checking skills in the flight operations to manage threats and errors effectively when we know the errors we make in the cockpit on daily operation. The result of LOSA indicates that the error detection rate should be enhanced since around the half of the errors went undetected. The areas which should be focused for enhancing the error detection are monitor, cross-check, the management of workload, automation and taxiway/ runway to manage errors effectively.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.437-441
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• 2022

In this study, we developed a neutron time-of-flight (nTOF) measurement system for a 1.7-MV tandem proton accelerator with a target covered with 300-nm-thick lithium (Li) layer. With implementation of beam chopping module after its ion source, the accelerator is configured to operate in pulsed-beam mode with a pulse width <50 ns at 20-kHz repetition rate. This enables the gamma flash-type nTOF measurement system to identify the neutron generated with 3-MeV proton beam energy. The nTOF system consists of a 30" cylindrical NaI(Tl) and four stilbene scintillation detectors. The NaI(Tl) scintillator is placed 50 cm from the Li target to measure the time of beam irradiation on the target, and the stilbene detectors are placed 2 and 2.4 m away to measure nTOF at each location. The nTOF system successfully measured the generated neutron energy at irradiated proton energies of 2.6 and 3.0 MeV with an average energy resolution of 15%.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.2
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• pp.171-178
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• 2023

PCM data is result of air-vehicle flight test, this data is distributed for each engineers to analyze its condition. Since line-of-sight between the air-vehicle and the ground receiver cannot always be secured, remote PCM data recording system was claimed to be required. In this paper multi-function PCM data recorder has been described. This PCM data recorder was intended to place on inside of flight object. It can record about two hours in 32 GB SD card with maximum 7 Mbps data rate. RS-422/485 and RJ-45 interface enhanced accessibility for users. 5 V and 1 A power consumption and 19.5 mm × 152.5 mm × 102.3 mm allow to connect with mobile PCM devices. It acquired more than 190-minutes data in 12-times flight test. Also, it achieved military standard environmental test MIL-STD-810G to prove its stability and solidness.